The present disclosure relates generally to semiconductor devices, and more particularly to programmable fuse and fuse circuits.
Fuse elements are widely used in semiconductor memory devices. In a typical application, a plurality of fuse elements are employed in a semiconductor memory device, e.g., a dynamic random access memory (DRAM) device. In general, each of the fuse elements includes a fuse which is selectively opened or severed in order to selectively disconnect the corresponding fuse element from the remainder of the circuit. The process of opening or severing a fuse is sometimes referred to as “blowing a fuse”.
There are two basic techniques currently in use for blowing a fuse. Namely, a radiation source such as a laser can be used to irradiate (burn) the fuse until it is opened, or an electrical current which dissipates sufficient heat to open the fuse (i.e., an electrical “overcurrent”) can be used. The process of opening a fuse of a fuse element (which typically also includes at least a MOS transistor) is frequently referred to as “programming” the fuse element. Unlike using the laser, the technique of programming a fuse element by using an electrical overcurrent can be performed even after the device has been packaged. For the purpose of this application, the technique of programming a fuse element by using an electrical overcurrent to blow the fuse thereof will be hereinafter referred to as “electrically programming,” or simply “programming,” the fuse element, and the fuse element which is susceptible to such programming will hereinafter be referred to as an “programmable fuse element,” or “electrical fuse,” or simply, “fuse.” Conventionally the electrical fuse can be programmed once, and once the fuse is programmed, it is irreversible as it is blown open. The electrical fuse that is limited to one time programming is referred to as the one-time programmable (OTP) fuse. Comparing to the OTP fuse, there are multiple-time programmable (MTP) fuses that are much needed in various applications. For example, floating gate based nonvolatile devices can be programmed for multiple times. The floating gate traps charges to differentiate the logic states that it represents. Charges can be injected or removed multiple times.
Desirable in the art of are additional designs that provide a multiple-time programmable resistance circuit using one-time programmable fuses.